The development database allows Londoners to access details on planning permissions granted in the capital since 2000. Users enter a postcode or click on an interactive map to view details of completed developments, those just starting or schemes awaiting the green light.
The facility aims to show individuals the type of developments that their local authorities are permitting. The service will also give planning professionals an overview of decisions to help them plan future developments.
Livingstone also announced extra funding to enhance the Planning Aid for London service, including appointing an independent adviser to give free planning-related advice to those who cannot afford professional help.
"Navigating the planning system can be daunting," said the mayor. "These initiatives will make a difference to individuals and professionals who want to know what development is being proposed, along with a point of contact to guide them through."
The London Development Database can be viewed via www.PlanningResource.co.uk.